SPAXX and FCASH can both serve as a Fidelity brokerage core position: the place where uninvested cash is held and where money is automatically taken for trades or received after sales. They are not the same product. SPAXX is a money market mutual fund; FCASH is an interest-bearing free credit balance payable on demand by Fidelity.
Availability depends on the account type and brokerage arrangement. Check the choices shown in your authenticated account rather than assuming both options are available.
SPAXX vs FCASH at a glance
| Feature | SPAXX | FCASH |
|---|---|---|
| Full name | Fidelity Government Money Market Fund | Fidelity Taxable Interest Bearing Cash Option |
| Legal form | Money market mutual fund | Free credit balance at the broker |
| Return label | 7-day yield, net of fund expenses | Interest rate set by Fidelity |
| Value | Seeks to maintain a $1.00 share price, but is not guaranteed to do so | Dollar cash balance payable on demand under account terms |
| Holdings | Primarily cash, U.S. government securities and fully collateralized repurchase agreements under the fund strategy | Fidelity may use and invest free credit balances under the customer agreement |
| FDIC insurance | No | Do not assume FDIC insurance; FCASH is not the FDIC bank sweep |
| Access for core transactions | Automatically used for eligible purchases, withdrawals and deposits | Automatically used for eligible purchases, withdrawals and deposits |
| Main risks | Fund, liquidity, interest-rate, counterparty and rare loss-of-NAV risk | Broker credit/custody and changing-rate risk under account terms |
Yield records: dates must match
Fidelity's fund page displayed a 3.30% 7-day yield for SPAXX as of July 7, 2026. The trading-account FAQ displayed a 1.82% FCASH interest rate as of December 12, 2025 when this article was reviewed on July 10, 2026. These are different dates and different measures, so they are not a clean current-rate comparison.
Before changing a core position, open the live SPAXX fund page and your account's current FCASH rate on the same day. Save the timestamp. Money market yields and broker-set cash rates can change without the account holder taking action.
A 7-day yield annualizes recent fund distributions after expenses; it is not a promised one-year return. FCASH interest accrues under Fidelity's stated method and rate. Compare expected annual dollars at your balance, not only the percentage headline.
SPAXX: structure and risk
SPAXX states an objective of seeking current income consistent with preservation of capital and liquidity. Its strategy normally places at least 99.5% of total assets in cash, U.S. government securities and/or fully collateralized repurchase agreements. As of the July 2026 records, Fidelity reported a $1.00 NAV, but a money market fund is still a security, not a bank deposit.
The fund is not FDIC-insured or guaranteed by a government agency. Government securities in a portfolio do not turn fund shares into a government guarantee. Review the current prospectus for fees, liquidity provisions, valuation and principal risks.
FCASH: structure and risk
Fidelity describes FCASH as a free credit balance payable on demand. It is not a mutual fund and has no expense ratio or NAV. Fidelity sets the rate and can change it. Account documents can permit the broker to use free credit balances in its business, which is one reason the rate and legal claim should be reviewed separately from a fund.
FCASH should not be confused with Fidelity's FDIC-Insured Deposit Sweep Program. If deposit insurance is a requirement, verify that the exact core label is the bank sweep and review participating banks and coverage limits.
SIPC protection is also different from FDIC insurance. SIPC may protect eligible customer cash and securities if a member brokerage fails and property is missing, within statutory limits; it does not guarantee yield or protect against market loss. Confirm how the exact account and balance are treated.
Liquidity and settlement
When either option is the core position, Fidelity says it processes cash automatically for purchases, sales, checks, electronic transfers and other eligible account activity. That operational convenience does not mean every deposit is immediately withdrawable. Collection periods, trade settlement, holds and account restrictions can still affect availability.
Test a small deposit, purchase and withdrawal if timing matters. Distinguish cash available to trade from cash available to withdraw.
Which factors should decide?
Use a same-day comparison:
- Is the option available for this exact account?
- What are today's FCASH rate and SPAXX 7-day yield?
- Do you understand fund risk versus a free credit balance?
- Does your cash need FDIC insurance, and is a separate bank sweep available?
- Are there account holds or transaction limits that affect access?
- How much annual dollar difference would the yield gap make after taxes?
- Are you intentionally holding cash, or has an investment allocation drifted?
Bottom line
SPAXX offers money market fund exposure and a market-linked yield; FCASH is a broker free credit balance with a rate set by Fidelity. Compare rates on the same date, read the exact account agreement and prospectus, and do not infer FDIC insurance from either the word cash or a stable $1 value. This comparison is educational and is not a recommendation to choose either position.
